EP 1 603 611 B1 discloses an injector where a user may set the dose. The principal assembly of a drug delivery device and its drive mechanism are disclosed in EP 1 603 611 B1, to which reference is made for further details. Such injectors have application where regular injection by persons without formal medical training occurs. This is increasingly common amongst those having diabetes where self-treatment enables such persons to conduct effective management of their diabetes. These circumstances set a number of requirements for pen-type injectors of this kind.
The injector must be robust in construction, yet easy to use both in terms of the manipulation of the parts and understanding by a user of its operation. In the case of those with diabetes, many users will be physically infirm and may also have impaired vision. Where the injector is to be disposable rather than reusable, the injector should be cheap to manufacture and easy to dispose of (preferably being suitable for recycling).
In the manufacture of such medical devices there are often advantages in producing a family of products based on a common device platform. For example, simplification of manufacturing processes or reductions in costs of tools are such advantages.
In addition, in some cases the settable maximum dose of the drug delivery device may not be appropriate for each of the drugs to be delivered. One example may be long acting insulin and short acting insulin. Another example may be to prevent children using such a drug delivery device from setting a too high dose.
Thus, there is a need for providing a reliable mechanism allowing choosing the appropriate maximum settable dose in a drug delivery device platform with a minimum of effort for changes compared to a standard device and a minimum of replacement parts.
In WO 01/54757 A1 a dose setting limiter is described having a first part formed as a dose setting dial and fitted over a rotary dose setting knob of the medical injector. The maximal allowable dose is preselected with the dose setting limiter disconnected from the housing of the medical injector by rotating a further part until a marker on said further part is placed over a desired maximal allowable dose indication on a scale. When dialling the first part clockwise a protrusion provided on the first part will abut another protrusion located on the further part once the preselected desired dose is reached, thereby preventing larger doses from being set. All movements during setting of a dose are rotational movements without axial components of the movements. Thus, the maximum distance a user may move the dose setting knob is limited to about 360° which either makes the maximum distance small or increases the overall dimensions of the device.
Further, WO 2006/089767 A1 discloses a dose setting mechanism comprising a dose setting member and a housing. The dose setting member is provided with a first stopping member which is permanently rotationally coupled to the dose setting member and may be adjusted in its axial position relative to the dose setting member. In addition, the housing is provided with a second stopping member which abuts the first stopping member if a preset maximum dose has been set such that a further dose can not be set.
In WO 2010/097125 A1 a dose setting mechanism comprising a tubular distal housing with threads on its inner surface is described, with said threads cooperating with a first thread segment on the outer circumference surface of a tubular dose limiting member. A tubular dose setting member is coaxially arranged inside the dose limiting member. A removable lock member is attached to the distal housing and comprises one elongated rib on its inner circumferential surface to interact with a protrusion of the dose limiting member in order to lock the dose limiting member in a certain position in a presetting phase. During dose setting a stop surface of the tubular dose limiting member interacts with an end surface of an outer thread of the dose setting member to limit the set dose.